Exactly. Worked amazingly well on my last car (even had one mode for windows-down, one mode for windows-up), but the Kia's doesn't seem to turn the sound up enough with increased speed, even with the windows up. Oh well, I guess it helps though.
Everyone is turning the system on, right? I had to turn mine on, as it was off from factory. Didn't even know the feature was there, but I was hunting for the Sirius display change and found the speed thinger.
This thread is over a year old, but to answer you quest jcbel there is no notification that the volume is changing it just slow increases the volume as the car goes faster. again as I stated before if you want to have better control of the volume you are better adjusting it manually.